11c05-1.php

来自「介绍PHP5的给类型函数应用」· PHP 代码 · 共 74 行

<?php
// A function that will accept and clean up CC numbers
function standardize_credit($num) {
    // Remove all non-digits from the string
    return preg_replace('/[^0-9]/', '', $num);
}

// A function to check the validity of a CC number
// It must be provided with the number itself, as well as
// a character specifying the type of CC:
// m = Mastercard, v = Visa, d = Discover, a = American Express
function validate_credit($num, $type) {
    // First perform the CC specific tests:
    // Store a few evaluations we will need often:
    $len = strlen($num);
    $d2 = substr($num,0,2);
    
    // If Visa must start with a 4, and be 13 or 16 digits long:
    if ( (($type == 'v') && (($num{0} != 4) ||
                !(($len == 13) || ($len == 16)))) || 
    // If Mastercard, start with 51-56, and be 16 digits long:
         (($type == 'm') && (($d2 < 51) || 
                 ($d2 > 56) || ($len != 16))) ||
    // If American Express, start with 34 or 37, 15 digits long:
         (($type == 'a') && (!(($d2 == 34) || 
                 ($d2 == 37)) || ($len != 15))) ||
    // If Discover: start with 6011 and 16 digits long
         (($type == 'd') && ((substr($num,0,4) != 6011) || 
                 ($len != 16))) ) {
        // Invalid card:
        return false;
    }

    // If we are still here, then time to manipulate and do the Mod 10
    // algorithm.  First break the number into an array of characters:
    $digits = str_split($num);
    
    // Now reverse it:
    $digits = array_reverse($digits);
    
    // Double every other digit:
    foreach(range(1, count($digits) - 1, 2) as $x) {
        // Double it
        $digits[$x] *= 2;

        // If this is now over 10, go ahead and add its digits, easier since
        // the first digit will always be 1
        if ($digits[$x] > 9) {
            $digits[$x] = ($digits[$x] - 10) + 1;
        }
    }

    // Now, add all this values together to get the checksum
    $checksum = array_sum($digits);
    
    // If this was divisible by 10, then true, else it's invalid
    return (($checksum % 10) == 0) ? true : false;
}

// Check various credit card numbers:
$nums = array(
    '344 2345 3466 4577' => 'a', '3794 2345 3466 4577' => 'a', 
    '4938748398324' => 'v', '4123-1234-5342' => 'v', 
    '51847293 84567434' => 'm', '5723x2345x2345x6161' => 'm', 
    '6011 6011 6011 6011' => 'd', '6012 392563242423' => 'd', 
    );
    
foreach ($nums as $num => $type) {
    $st = standardize_credit($num);
    $valid = validate_credit($st, $type);
    $output = $valid ? 'Valid' : 'Invalid';
    echo "<p>{$st} - {$type} = {$output}</p>\n";
}
?>